Cultural and aesthetic standards have influenced the permissible level of human and environmental malodors and control of these odors has been the focus of investigation for many centuries. In general, these investigations have been focused on either of two approaches, namely: (a) odor masking, in which a substance of strong yet relatively pleasant odor is introduced into the proximity of a less pleasant odor source with the intent of overburdening the olfactory receptors with the dominant pleasant odor, or (b) sequestering the undesired odorous substance in a non-volatile form either by chemical reaction, adsorption or absorption on a sorbent material exhibiting a preference for the odorous substance.
In general, articles made of fabric absorb odors and this fact has a pejorative consequence as it relates to the perceived cleanliness of said articles. For example, it has long been recognized that items which are comprised of fabric, especially articles of clothing, can be clean in the sense that the article is free of dirt (i.e. has not been worn since it was laundered), yet this article is rendered "dirty" due to exposure of the article to certain malodors inter alia cigarette and cigar smoke, or fried food odors. This exposure can often occur when the item of apparel is simply hanging in a closet. Although it is frustrating when articles of "common apparel" require re-laundering due to malodor absorption, the consumer is faced with both inconvenience and added expense when certain items are prematurely rendered unfit for wear, for example, items comprised of natural fur or items requiring "dry-cleaning". Indeed, articles such as rugs, carpeting and draperies which are not easily removable nor easily cleaned, present a particular problem when exposed to persistent malodor sources.
Odor masking, although effective in the short term, has certain limitations. First, masking does not remove or eliminate the source of the malodor. Secondly, when scents and perfumes are used to overcome malodors, the user must make sure an effective and constant level of masking agent is present to avoid too low a level of masking agent that may not be sufficient to cover-up the malodor. In turn, too high a level of masking agent may itself produce an undesirable effect. The premature depletion of the masking agent can be an additional concern.
Sequestration has thus become the method of choice for elimination and control of both human and environmental malodors. The more effective approach has been to sequester the undesired malodor primarily by adsorption. Attempts have previously been made to re-freshen clothing, rugs, draperies, and the like, by applying malodor absorbic materials. Many of these processes have been successful, yet the fabric which has been deodorized is typically left without the desired "fresh" or "clean" scent desirable to the consumer.
Accordingly, there remains a need in the art for a malodor control composition which absorbs malodors thereby removing unwanted smells and at the same time releasing desirable fragrances which provide an aesthetically pleasing environment. There is especially a need for odor absorbing compositions which have the capacity to release enduring fragrances which are not themselves absorbed by the malodor absorbing agent.